【作者】 李伟；

【导师】 叶树林； 魏昕；

【作者基本信息】 广东工业大学 ， 机械制造及其自动化， 2008， 硕士

【摘要】 基于线电极的电火花展成加工是一种特殊的电火花加工技术,与传统的使用棒状电极的电火花铣削加工相比,其最大优点是可通过线电极的移动来补偿加工中的电极损耗。本论文在对基于线电极的电火花展成加工伺服控制过程和伺服特点进行全面深入分析的基础上,创造性的提出了双向伺服进给控制策略。对推动回转类电火花加工工艺的发展和丰富电火花加工的进给控制技术具有重要意义。本文首先分析了基于线电极的电火花展成加工的放电特征。通过建立的放电间隙变化的数学模型,得出该工艺具有回转运动的周期性和放电的局部性等特点;线电极的回转降低了电弧放电继续恶化的可能,从而将正常放电和电弧放电均可视为有效放电;该工艺还具有放电击穿延时较为随机等特点。为了有效的实现对基于线电极的电火花展成加工的伺服控制,针对目前单一伺服进给控制策略加工效率不高的缺点,首次提出了周向伺服控制与径向伺服控制相结合的双向伺服进给控制策略。双向伺服进给控制策略是指在周向与径向不同的控制周期内,考察间隙放电状况和比较决策,周向进给和径向进给联动进给,实现成型加工的目的。双向伺服进给控制策略增大了时间利用率,提高了加工效率。周向伺服控制与径向伺服控制分别采用自适应PID控制和模糊控制,并开发出控制算法。此外,研制了基于线电极的电火花展成加工的伺服控制系统。系统采用主从式上位机和下位机两级结构。下位机读取放电状态信息,控制步进细分驱动模块,根据上位机发出指令对周向和径向进行伺服控制,同时采用RS232串行口通讯,将当前加工信息传输到上位机并显示出来;上位机主要完成人机交互及数据处理等功能。控制系统在检测方法上采用了基于CPLD的间隙放电状态检测电路。最后,采用研制的基于线电极的电火花展成加工装置和控制系统,进行了控制系统的加工性能实验和对比实验研究。研究结果表明,本文研制的控制系统能精确有效地实现控制。在相同实验条件下,双向伺服控制比径向伺服控制加工效率有显著提高。更多还原

【Abstract】 EDM with wire electrode generating machining appears to be a particular kind of EDM technology. Comparing with conventional Electrical Discharge Milling (EDM Milling) using cylindrical electrode, the distinct advantage is electrode compensation via the wire electrode slow traveling. First, servo feature and characteristic is analyzed, two-direction servo feed control method has been put forwarded creativitily. Furthermore , the technology has the potential significant influence on the development of EDM and enriches servo feed control technology.To begin with, the discharge characteristics in EDM Milling with wire electrode have been analyzed. It’s found that the technology has the characteristics of periodicity of revolving and discharge localization through the mathematical model of the gap states. It’s also believed that the normal discharge and arc are both effective discharge for the revolving of wire electrode. Furthermore, it’s found that the breakdown time is random.In order to servo control EDM with wire electrode generating machining validly, against low efficiency of single radial servo control at the moment, two-direction servo feed method of circumferential servo control and radial servo control is put forward . It means in the different control period of circumferential and radial, inspects gap state, circumferential servo control and radial servo control servos at the same time to achieve machining. Two-direction servo feed method amplifies time distribution, improves machining efficiency. Circumferential servo control and radial servo control use self-adaptive PID control and fuzzy control respectively and develop control program.In addition, servo control system of EDM based on wire electrode is designed. Master-slave two grade structure is used in the system. The slave reads discharge state message, controls step motor subdivision drive module, according to instruction from the upper PC to servo control. At the same time, adopt RS232 serial communication to transport current machining message to upper PC and show it; Upper PC mainly achieves human-machine interactive and data processing so function. In the means of detection, the control system adopts detection circuit of gap discharge state based on CPLD.At last, using the equipment and control system that was designed in this dissertation, the experiments of control system were carried out. The results show that control system can control processing availably. Under the same experiment condition and compared with radial feed, two-direction feed could improve machining efficiency remarkablely.更多还原